The disclosure relates to an illumination unit that emits light including a laser beam, and a display that displays an image by using such an illumination unit.
In general, an optical module, which is one of main parts of a projector (a projection-type display), is configured to have an illumination optical system (an illumination unit) and a projection optical system. The illumination optical system includes a light source, and the projection optical system includes a light modulation device. In the field of such a projector, small (palmtop) and lightweight portable projectors called “micro-projector” have become widespread in recent years. In this micro-projector, LED (Light Emitting Diode) has been mainly used as the light source of the illumination unit.
Meanwhile, lately, lasers have been receiving attention as a new type of light source for the illumination unit. For instance, following the commercialization of high-output blue semiconductor lasers and red semiconductor lasers, development of green semiconductor lasers has been underway and is about to reach a practical level. Against this backdrop, there has been suggested a projector in which single-color lasers (semiconductor lasers) for three primary colors of red (R), green (G), and blue (B) are used as a light source of the illumination unit. Use of the single-color laser as the light source makes it possible to obtain a projector in which a color reproduction range is wide and power consumption is low.
Further, in recent years, there has been a demand for improvements in size (downsizing) and brightness of portable projectors. This is because, in existing small semiconductor lasers, although output is considered to be high, brightness tends to be insufficient. Therefore, development of semiconductor lasers with higher output has been vigorously pursued.